From f1cf57daa44f9c2f4921e7f520c2258421c44998 Mon Sep 17 00:00:00 2001
From: Than McIntosh <thanm@google.com>
Date: Mon, 9 Nov 2015 12:18:36 -0500
Subject: Use symlink in /tmp to obscure sysroot prefix.

Create a link in /tmp to the prebuilt sysroot and
pass the link location to the gcc configure script;
this is intended to avoid hard-coding buildbot
pathnames into the gcc binary.

Bug: 25513824
Change-Id: I49dddde6f91a9737a8b8a27802acfc7133dd63af
---
 build-gcc.sh | 29 ++++++++++++++++++++++++++---
 1 file changed, 26 insertions(+), 3 deletions(-)

(limited to 'build-gcc.sh')

diff --git a/build-gcc.sh b/build-gcc.sh
index cecc53594..1203fa194 100755
--- a/build-gcc.sh
+++ b/build-gcc.sh
@@ -76,6 +76,9 @@ register_var_option "--enable-languages=<name>" ENABLE_LANGUAGES "Experimental:
 BUILD_DEBUGGABLE="no"
 register_var_option "--build-debuggable=<yes|no>" BUILD_DEBUGGABLE "Experimental: build debuggable version of gcc"
 
+OBSCURE_PREFIX="yes"
+register_var_option "--obscure-prefix=<yes|no>" OBSCURE_PREFIX "Experimental: obscure sysroot prefix dir by linking to it from /tmp"
+
 
 register_jobs_option
 register_canadian_option
@@ -214,6 +217,21 @@ if [ $? != 0 ] ; then
     exit 1
 fi
 
+PREFIX_LOCATION=$TOOLCHAIN_INSTALL_PATH
+BUILD_SYSROOT_LOCATION=$TOOLCHAIN_BUILD_SYSROOT
+
+# If enabled, use symbolic link to obscure prefix location (b/25513824)
+if [ "$OBSCURE_PREFIX" == "yes" ]; then
+    TAG=`echo $ARGV $$ $RELEASE | md5sum | cut -f1 -d" "`
+    rm -f /tmp/$TAG
+    ln -s $PREFIX_LOCATION /tmp/$TAG
+    PREFIX_LOCATION=/tmp/$TAG
+    BUILD_SYSROOT_LOCATION=/tmp/$TAG/sysroot
+elif [ "$OBSCURE_PREFIX" != "no" ]; then
+    echo "error: illegal value for --obscure-prefix option (must be 'yes' or 'no')"
+    exit 1
+fi
+
 # configure the toolchain
 #
 dump "Configure: $TOOLCHAIN toolchain build"
@@ -366,15 +384,15 @@ $BUILD_SRCDIR/configure --target=$ABI_CONFIGURE_TARGET \
                         --host=$ABI_CONFIGURE_HOST \
                         --build=$ABI_CONFIGURE_BUILD \
                         --disable-nls \
-                        --prefix=$TOOLCHAIN_INSTALL_PATH \
-                        --with-sysroot=$TOOLCHAIN_BUILD_SYSROOT \
+                        --prefix=$PREFIX_LOCATION \
+                        --with-sysroot=$BUILD_SYSROOT_LOCATION \
                         --with-binutils-version=$BINUTILS_VERSION \
                         --with-mpfr-version=$MPFR_VERSION \
                         --with-mpc-version=$MPC_VERSION \
                         --with-gmp-version=$GMP_VERSION \
                         --with-gcc-version=$CONFIGURE_GCC_VERSION \
                         --with-gdb-version=none \
-                        --with-gxx-include-dir=$TOOLCHAIN_INSTALL_PATH/include/c++/$GCC_VERSION \
+                        --with-gxx-include-dir=$PREFIX_LOCATION/include/c++/$GCC_VERSION \
                         --with-bugurl=$DEFAULT_ISSUE_TRACKER_URL \
                         --enable-languages=$ENABLE_LANGUAGES \
                         $EXTRA_CONFIG_FLAGS \
@@ -471,6 +489,11 @@ fi
 # remove sysroot
 run rm -rf "$TOOLCHAIN_INSTALL_PATH/sysroot"
 
+# clean up link in /tmp if needed
+if [ "$OBSCURE_PREFIX" == "yes" ]; then
+  rm -f $PREFIX_LOCATION
+fi
+
 # Remove libstdc++ for now (will add it differently later)
 # We had to build it to get libsupc++ which we keep.
 run rm -rf $TOOLCHAIN_INSTALL_PATH/$ABI_CONFIGURE_TARGET/lib/libstdc++.*
-- 
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